The present invention relates to a device for radial adjustment of a cutting insert in rotary cutting tools for chipforming machining of preferably metallic workpieces, wherein the cutting insert is provided on a tool element, such as a drill or a shank end mill, which is mounted in a tool holder, comprising a sleeve member which is arranged rotatably between the tool holder and the tool element, said sleeve member being rotatable relative to the tool holder about a first axis and relative to the tool element about a second axis, said second axis being radially spaced from said first axis, thereby causing the tool element and thus also the cutting insert to be displaced radially relative to the tool holder upon rotation of the sleeve member relative to the tool element and the tool holder.
A device of this type is disclosed in U.S. Pat. No. 2,991,667. This prior art device is intended for reaming pre-drilled holes and cannot be used in connection with tools having centre inserts, i.e. tools in which the cutting edges of the inserts extend from the rotational axis of the cutting tool, since the sleeve member is rotatable relative to the tool holder about an axis which coincides with the rotational axis of the cutting tool.
The object of the present invention is to provide a device of the above type in which cutting tools having centre inserts can be radially displaced without jeopardizing the function of the cutting tool.
Another object of the invention is to provide a radial adjustment of the cutting insert as accurate as possible.
A further object of the invention is to provide a device in which the length of the tool holder is no larger than that of tool holders for tool elements which do not allow radial adjustment of the cutting insert.
A still further object of the invention is to provide a device in which the unbalanced forces created by radial adjustment of the cutting insert are as small as possible.
The above and other objects are attained by giving the invention the characterizing features stated in the appending claims.